TECUMSEH, Ontario — For 16 seasons, Bob Probert’s fists were two of hockey’s most notorious weapons, winning most of his 246 fights and feeding the N.H.L.’s fondness for bare-knuckle brawling.

But the legacy of Probert, who died last July of heart failure at 45, could soon be rooted as much in his head as his hands. After examining Probert’s brain tissue, researchers at Boston University said this week that they found the same degenerative disease, chronic traumatic encephalopathy, whose presence in more than 20 deceased professional football players has prompted the National Football League to change some rules and policies in an effort to limit dangerous head impacts.

Although the National Hockey League has taken steps recently to reduce brain trauma — banning blindside hits to the head, for example — it has nonetheless continued to allow the fighting that some say is part of the sport’s tradition and appeal. Teams continue to employ and reward players like Probert, who are known as enforcers because of how they intimidate opponents.

Hockey’s enduring tolerance for and celebration of fighting will almost certainly be tested anew now that Probert, more pugilist than playmaker, has become the first contemporary hockey player to show C.T.E. after death. Boston University’s Center for the Study of Traumatic Encephalopathy had previously diagnosed the disease in a long-retired player, Reggie Fleming, a 1960s-era enforcer who played before the full adoption of helmets.

“How much is the hockey and how much is the fighting, we don’t really know,” said Dr. Robert Cantu, co-director of the Boston University center and a prominent neurosurgeon in the area of head trauma in sports. “We haven’t definitely established that the skills of hockey as a sport lead to a certain percentage of participants developing C.T.E. But it can happen to hockey players, and while they’re still relatively young.”

Donald Fehr, the executive director of the players union, said the findings on Probert could not be taken lightly.

“Obviously, when you have a finding like this, it raises concerns and it bears serious examination,” Fehr said. “My impression is that the players want the best medical and scientific evidence that they can find so they make their decisions. They’re not looking to hide from the data. I don’t think anyone in hockey is looking to hide from the data.”

When informed of the Probert finding, Bill Daly, deputy commissioner of N.H.L., said he could not comment beyond his immediate reaction:

“We’re aware of what B.U. is doing, and we’ve met with them before,” Daly said. “It’s interesting science. We have interest in it. To the extent that the science itself starts to suggest certain conclusions, obviously we’re open to accepting that and addressing that moving forward. But we can’t take steps tomorrow based on what we’re finding out today.”

Some of the league’s top players, including the Pittsburgh Penguins’ Sidney Crosby, have missed significant time this season after sustaining concussions in the course of play. Commissioner Gary Bettman said earlier this year that concussions resulting from fights had increased.

Probert was not the average player — he reveled in extremes both on and off the ice, primarily in fighting, drinking heavily and embracing other physical risks.

Probert’s posthumous autobiography, “Tough Guy,” gleefully offers details of his 3,300 career penalty minutes — fifth in N.H.L. history — and recounts so many brawls with enforcers like Tie Domi and Marty McSorley that it requires 11 pages to list them all. He scored 163 goals in his career from 1985 through 2002, for the Detroit Red Wings and the Chicago Blackhawks, but was so known for his fighting that a 2007 Hockey News poll rated him the greatest enforcer in hockey history.

Probert drank heavily beginning in his youth in Windsor, Ontario, and he used cocaine to the point that he served 90 days in a Minnesota prison and was suspended by the N.H.L. multiple times, including for the entire 1994-95 season. His police record included driving citations, bar fights and assaults on police officers. While boating last July 5 on Lake St. Clair, near his home in Tecumseh, Probert collapsed and died of heart failure, including an 80 percent blockage of the left coronary artery.

Many athletes later found with C.T.E. — whose test for abnormal protein deposits in brain tissue can be administered only after death — presented symptoms like drug abuse, impulse control and impaired memory only in the years before they died, suggesting that the disease contributed to it.

Probert’s case is considerably more difficult to interpret, Cantu said, because of his history. Cantu and other Boston University researchers declined to discuss any further specifics regarding Probert before publication in an academic journal.

Probert’s widow, Dani, said in an interview at their home on Tuesday that the B.U. group had said that her husband’s C.T.E. was less developed than that found in most football players of similar age. She added that in his final few years, Probert exhibited some behavior uncharacteristic to him, especially memory loss and a tendency to lose his temper while driving.

Cantu, while not speaking about Probert’s substance abuse specifically, also emphasized that “as of now, the medical community is not aware that any drug abuse, including alcohol, leads to” chronic traumatic encephalopathy.

Dani Probert said that her husband was aware of growing concern about C.T.E. among athletes in contact sports, and that they had discussed it soon before he died after a “60 Minutes” feature on the subject.

“I remember joking with him, ‘Wouldn’t your brain make a nice specimen?’ ” she said. “He started questioning whether he would have it himself. He told me that he wanted to donate his brain to the research when he died. Who would have thought that six months later it would be happening?”

Chris Nowinski, a co-director of the Boston University research group, said that 10 other professional hockey players, almost all of whom played in the N.H.L., had pledged to donate their brains upon death. More than 100 professional football players have done the same, including Dave Duerson, the former Chicago Bears star and players union official who committed suicide two weeks ago.

Keith Primeau, who played with Probert in Detroit for several seasons in the early 1990s, arranged to donate his brain several months ago. Primeau sustained four documented concussions during his career but said in a telephone interview that he might have incurred others in fights that he did not recognize at the time.

“I was buckled a couple of times from a blow to the chin,” said Primeau, who had 98 fights in 15 N.H.L. seasons. “I don’t think it contributed to my overall concussion situation, but I wouldn’t discount it, either.”

Dani Probert said she learned of her husband’s having C.T.E. in early January but only recently became comfortable acknowledging it publicly. She said she would begin encouraging other hockey players to donate their brains, and raising awareness about the possible health risks of sports-related head trauma.

“In my heart of hearts, I don’t believe fighting is what did this to Bob,” she said. “It was hockey — all the checking and hits, things like that.”

She said those words just feet from a huge painting of Bob Probert that hangs in tribute to his hockey career. He is shown punching an opponent. On the canvas is scrawled a message from the artist:

“Gladiator as depicted by the Romans is a professional combatant or captive who entertains the public by engaging in combat. When it’s done for your team and your city, you’re known as a hero.”